Method of forming a pigment image from a pigment-resin toner image

ABSTRACT

A method of forming a pigment image from a pigment-resin toner image by exposing the pigment-resin toner image to a solvent for the toner resin resulting in the resinous portion of the toner being dissolved away leaving a pigment image on the substrate.

United States Patent [72] Inventor William L. Goffe Webster, N.Y. [21] Appl. No. 32,596 [22] Filed Apr. 28, 1970 [45] Patented Oct. 26, 1971 [73] Assignee Xerox Corporation Stamford, Conn. Continuation-impart of application Ser. No. 570,924, Aug. 8, 1966, now abandoned.

[54] METHOD OF FORMING A PIGMENT IMAGE FROM A PIGMENT-RESIN TONER lMAGE 15 Claims, 4 Drawing Figs.

[52] U.S.Cl 96/1.4,

96/l,1l7/l7.5, 117/37, ll7/l.7, 118/637 Primary ExaminerGeorge F. Lesmes Assistant Examiner-John C. Cooper, 111

Attorneys-James J. Ralabate, David C. Petre and Michael H.

Shanahan ABSTRACT: A method of forming a pigment image from a pigment-resin toner image by exposing the pigment-resin toner image to a solvent for the toner resin resulting in the resinous portion of the toner being dissolved away leaving a pigment image on the substrate.

PATENIEDBBI 26 mt I I I I I 1 FIG. 2

INVENTOR. WILLIAM L. GOFFE METHOD OF FORMING A PIGMENT IMAGE FROM A PIGMENT-RESIN TONER IMAGE CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending application under the same title filed Aug. 8, 1966, Ser. No. 570,924, now abandoned. The disclosure of that application is hereby incorporated by reference into the present application.

BACKGROUND OF THE INVENTION This invention relates in general to xerography, and more specifically to a system of forming an image.

In the art of xerography, as originally disclosed by Carlson in U.S. Pat. No. 2,297,691, and as further described by many related patents in the field, a xerographic plate containing a photoconductive insulating layer is first given a uniform electrostatic charge in order to sensitize its entire surface. The plate is then exposed to a source of activating electromegnetic radiation such as light, X-ray or the like, which selectively dissipates the charge in the illuminated areas of the photoconductive insulator while leaving behind a latent electrostatic image in the nonilluminated areas. This latent electrostatic image is then developed and made visible by depositing finely divided marking particles or toner on the surface of the photoconductive insulating layer. If desired, the toner particles may be transferred to a second surface, such as a sheet of paper, and fixed in place thereon to form a permanent visible reproduction of the original image.

The latent image may be developed by any convenient method. Typical methods include cascade, magnetic brush, aerosol, dusting by hand, etc.

In general, the toner material consistsof one or more organic resins, as a powder base, and a coloring material to impart the desired color to the powder and to permanently make a mark upon the surface to be developed. Typical toners and development techniques are adequately set forth in the following U.S. Pats. No. 2,297,691; Reissue US. Pat. Nos. 25,136; 2,618,551; 2,618,552; 2,638,415; 2,659,670; 2,788,288; 2,917,460; 3,041,169; 3,179,342; and 3,212,888.

It can be seen from the above, that the final image formed by the toner particles generally consists of an organic resinous binder having dispersed therein, and/or embedded at the surface thereof, marking material or coloring pigment, hereafter referred to as pigment. Due to the necessity of the proper triboelectric relationship such as that used in cascade, magnetic brush, and other modes of development, wherein the carrier bead electrostatically attracts pigment-resin toner particles to the bead, it is preferred that a pigment-resin toner material be used in order to easily control the proper triboelectric relationship between the developer mixture of carrier and toner, and the electrostatic image being developed. That is, the pigment may have characteristics unsuited for the above or other development modes which can be overcome by encasing it in a resinous or other material that has the required triboelectric characteristics. The use of such materials also provides a convenient means of handling developing material up to the point of forming an image on a desired background. There is, however, a need for a convenient method of forming a pigment image free from a resinous base material in that a pigment image has unique properties different and advantageous over those of a pigmentresin toner image. For example, an image formed of pigment particles has special application such as in the making of printing plates, or being used as a resist to etch a substrate. Additionally, a pigment image may be wetted or transferred by methods distinct from that of a toner image. A pigment image which could be formed from a pigment-resin image would provide the further advantage of allowing a pigment-resin toner image to be initially formed, and at the desired time, formingsaid pigment image at the convenience of the user. For example,-the resin may serve to protect or isolate the pigment dur ing shipment or storage.

There is, therefore, a need for a method of developing which provides a method of forming a pigment image from an original pigment-resin toner image.

It is, therefore, an object of this invention to provide a method of forming a pigment image which overcomes the above-noted disadvantages.

It is another object of this invention to provide a system of reducing a pigment-resin toner image to a pigment image.

It is another object of this invention to provide a method of producing a pigment image.

It is a further object of this invention to provide a developing system which yields an improved image.

It is yet a further object of this invention to provide a developing system in which conventional pigment-resin toner particles are converted to a pigment image.

The foregoing objects and other are accomplished in accordance with this invention by providing a method of reducing a charged pigment-resin toner image to a pigment image wherein a conventional pigment-resin toner image is first formed on the desired backing and reduced to a pigment image by exposing said pigment-resin toner image to a solvent for the toner resin only. The toner image is electrically charged prior to, during or subsequent to its formation, e.g., by triboelectric methods or by exposure to electrostatic charge generating apparatus. Exposure to said solvent results in the resinous portion of the toner being dissolved away leav-. ing a pigment image left on the substrate without any noticeably loss of resolution or density.

The pigment-resin toner material adaptable for this invention may be any conventional material such as those already defined in the art, and referred to in the long list of patents above. Any variety of softenable resinous materials which are suitable for a toner may be used. Typical materials include Staybelite Ester 10, a 50 percent hydrogenated glycerol rosin of the Hercules Powder Co., Piccotex 100 a styrene-type resin of Pennsylvania Industrial Chemical Co.; Araldite 6060 and 6071, epoxy resins of Ciba; and Veliscol X-37, available from Velsicol Chemical Corp.; 5 percent weight polycarbonate in CI-ICL,; 20 percent weight piccodione in toluene; 20 percent weight silicone resin in toluene;

Polyolefins; such as polyethylene; polypropylene; chlorinated polyethylene; chlorosulfonated polyethylene,

Vinyl & Vinylidenes; such as polystyrene; polymethylstyrene; acrylic polymers such as polymethyl methacrylate, polyacrylic acid, polyacrylonitrile; polyvinyl esters such as polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral; polyvinyl chloride; polyvinyl carbazole; polyvinyl ethers, polyvinyl ketones,

Fluorocarbons; such as polytetrafluoroethylene; polyvinyl fluoride; polyvinylidenefluoride; polychlorotrifluoroethylene, Heterochain thermoplastics; such as polyamides such as I polycoproloctamo, polyhexamethylene adipomide; polyesters such as polyethylene terephthalate; polyurethanes; polypeptides such as casein, zein; ether and acetal polymers such as 'polyoxymethylene, polyglycol, polysulfides; polycarbonates;

eellulosic polymers such as viscose, cellophane, cellulose acetate and mixtures and copolymers thereof, and many more.

The pigment material used to form the pigment-resin toner may consist of any suitable material which is insoluble in the resin solvent and meets the needs of a particular application. Typical pigments are carbon black, garnet, iron oxide, and any dyes insoluble in a given solvent, such as for example, Prussian blue, and many others.

The solvent may consist of any suitable fluid in which the resinous toner material dissolves while leaving uneffected the supporting substrate and pigment in the form of the original image. If desired, heat may be used to soften the resin prior to exposure to the liquid solvent. In addition, a prior treatment with solvent vapors, liquid and/0r heat followed by exposure to a liquid solvent may also be employed. The only requirement of the solvent is that it be a solvent for the resin only, and that it be substantially insulating in a sense that the charged image is not discharged electrically by exposure to the solvent.

A noninsulating solvent may be used to dissolve away the resin if the resin is-first softened by other suitable means, e.g., by exposure to an insulating solvent or heat or by a combination of the two. Typical solvents include without limitation; cyclohexane, Freon 113, Sohio Odorless Solvent 3440, pentane, heptane, toluene, trichloroethynene, methyl ethyl ketone, methylene chloride, acetone, etc.

In general, a few seconds of immersion in a liquid solvent is sufficient to dissolve away the resin. The time of exposure to the solvent is in no way critical inasmuch as the substrate and pigment are selected so as to be substantially insoluble in the solvent. The dissolving process is time dependent, however, and the toner image is softened before it is dissolved away. Furthermore varying the duration of exposure to the solvent permits different quantities of resin to be dissolved away.

Although the particle size of the pigment-resin toners contemplated by this invention is not critical, the particle diameter of said toners usually range between about 1 to 30 microns in diameter. These materials may be manufactured by any convenient method such as set forth in the large number of patents already mentioned above. The patent to Solar, U.S. Pat. No. 2,917,460, shows a suitable method of manufacturing pigment-resin toners.

DESCRIPTION OF THE DRAWINGS The advantages of this improved method of forming an image will become apparent upon consideration of the follow ing disclosure of the invention; especially when taken in conjunction with the accompanying drawings wherein:

FIG. I is a schematic sectional view showing a charged pigment-resin toner image on an insulating substrate.

FIG. 2 is the same view of the pigment-resin toner image of FIG. 1 during the initial stages ofexposure to a resin solvent.

FIG. 3 is the same view as FIG. 2 after treatment with the resin solvent.

FIG. 4 is a side elevation schematic view in section of a xerographic machine adapted for continuous and automatic operation typical of apparatus for forming conventional pigment-resin toner images.

DETAILED DESCRIPTION Referring to FIG. 1, reference character denotes an insulating substrate. An electrostatically charged pigment-resin toner image 11 consisting of a resin 12 having dispersed therein a pigment 13 is deposited in image configuration on substrate 10.

As shown in FIG. 2, the charged toner image is then immersed in a bath 14 of liquid solvent which is a solvent for resin 12 only, resulting in the insoluble pigment being electrostatically attracted to the insulating substrate while the soluble resin is being dissolved in the solvent. FIG. 3 shows the resultant pigment image 13 remaining on the insulating substrate 10, with the resin 12 being completely dissolved away from the surface. It can thus be seen that through the sequence shown in FIGS. 1 through 3, that a pigment-resin toner image is converted to a pigment image by exposure to a solvent for the resin only. After treatment with the solvent liquid, the pigment image is retained on the substrate without any noticeable loss in the original image resolution or density. Although at this point the pigment is not chemically fixed, it is strongly electrostatically attracted to the substrate, and if desired, any common fixitive may be applied to the pigment image to render it more permanent. The fixitive may include the resin if less than all the resin is dissolved away during its exposure to the solvent.

The substrate for transforming the pigment-resin toner image to a pigment image may be any suitable material which will not dissolve in the solvent. It may be an insulator or a conductor such as those normally used in the xerographic art. The substrate may be a metallic sheet, web, foil, cylinder, or the like; a sheet of glass with an electrically conductive coating or a conductive coated sheet of paper or stable plastic. Typical insulators include paper and plastics such as Mylar.

The pigment image formed by this invention may be adaptable to any method of forming pigment-resin toner image which are electrostatically attracted to a substrate such as in xerography wherein a conventional xerographic image such as that shown in any of the above-mentioned patents is formed on a photoconductive layer which is then transferred to a suitable support member such as that illustrated in FIG. l-3. The transferred pigment-resin toner image is then converted to a pigment image through the use of a resin solvent as has already been described above.

Also included within the scope of this invention is the conversion of a pigment-resin toner image to a pigment image, wherein the original pigment-resin toner image is formed on a substrate having an overcoating of a soluble resin. This overcoating may be the same material as the toner resin or a different soluble resin. It should be understood, however, that the substrate must still be substantially insoluble, while both resins are dissolved when immersed in the solvent.

U.S. Pat. No. 3,301,126 discloses xerographic method and apparatus for the rapid and automatic formation of pigment resin toner images which can be converted to pigment images by the present application. Typically, the images formed by xerographic systems are transferred to paper substrates and are fixed to the paper by heat and/or pressure. The fixing of a pigment-resin toner image normally involves softening the resin sufficiently to bond the toner particles comprising the image to each other and to the substrate. To insure that a fixed image is charged, the image can be exposed to electrostatic charge generated by a corona discharge device such as shown in U.S. Pat. No. 2,777,957 to Walkup. A charged, fixed, pigment-resin toner image is converted to a pigment image as illustrated in FIGS. 1-3 by exposing the fixed image to a solvent to dissolve away the resin.

The xerographic system to FIG. 4 is typical of systems capable of making pigment-resin toner images. All of the processing stations referred to by letters are conventional in the xerographic art and greater detail in regard to them is prevalent in the literature including the above U.S. Pat. No. 3,301,126. For the purpose of the present disclosure, the several xerographic processing stations in the path of movement of the xerographic drum 15 having a suitable photoconductive layer 16 may be described as follows:

A charging station A, at which a uniform electrostatic charge is deposited on the photoconductive layer 16 by means of a corona discharge device 17;

An exposure station B, at which a light or radiation pattern is directed onto the photoconductive layer 16 by appropriate projection apparatus 18 to dissipate the charge in the exposed areas thereby forming a latent electrostatic image;

A development station C, at which a xerographic developing material including carrier beads and pigment-resin toner particles are cascaded over the latent electrostatic image by the buckets 19 coupled to endless belt 20 with the toner particles adhering to the drum in the areas of charge forming a pigment-resin toner image;

A transfer station D, at which the toner image is electrostatically transferred to a substrate 22 by means that include the corona discharge device 23;

A fixing station E, at which the transferred toner image is fused to the substrate by means of the radiant heater 24;

A drum cleaning station F, at which the drum surface is brushed by the rotary brush 25 to remove residual toner particles remaining on the drum after the transfer of the pigmentresin toner image to the substrate.

The development material cascaded over the drum at the development station is stored in the lower or sump portion 26 of the development housing 28. The buckets l9 scoop up the developer in the sump and pour it onto the drum as they travel around the pulleys 29 and 30 on the belt 20. The carrier beads and toner particles are selected such that their mechanical interaction triboelectrically imparts a charge polarity to the toner particles which causes them to be attracted to the drum in the areas of the latent electrostatic image. As between the resin and pigment making up the toner particles, the desired triboelectric property of a toner particle is due to the resin. Consequently, a wide variety of materials may comprise the pigment which normally would be unsuited for image forming processes. That is, the toner particles contained in the developer housing may include conventional xerographic toner or toner comprising pigments having special properties combined with a suitable resin for the above xerographic cascade development process or other developing processes.

The corona discharge device 23 at the transfer station D deposits on the back of the substrate 22 a charge having a polarity that electrostatically attracts the toner image from drum to the substrate. The fuser or heater 24 can be inactivated, i.e., turned off, so the electrostatically tacked toner image can be converted to a pigment image by exposing it to a solvent. Alternatively, the toner image can be fixed to the substrate at the fixing station E by activating the fuser which may be desirable to facilitate the shipment and/or storage of the toner image prior to converting it to a pigment image. The substrate 22 is shown as a web but it is understood that substantially similar xerographic systems are available capable of handling substrates in the form of sheets.

This invention is also applicable to images which are formed by other techniques. These images may be formed on an insulator or on a conductive substrate such as aluminized Mylar, by first forming a uniform layer of a pigment resin toner over the entire support surface. A selective mask in the form of the desired image is then placed over the pigment-resin toner coated support. An electrostatic charge is then applied to the selected areas by means of the corona discharge device such as that shown in the above mentioned U.S. Pat. No. 2,777,957 to Walkup, with the mask or stencil in the form of the desired image. Depending on the particular pigment-resin toner, the toner is either positively or negatively charged to a retained voltage of between about 2 to 160 volts, or higher. The uncharged toner not being electrostatically attracted to the conductive substrate is then removed from the substrate by mechanical agitation or by a jet of air leaving the charged toner particles in image configuration whereupon the pigment-resin toner image is then selectively treated by a solvent for the resin only as already described above.

In another embodiment, the supporting conductive substrate is uniformly overlaid with an adhesive or tackifiable material such as petrolatum, fingerprint grease, Kodak Photoresist (available from Eastman Kodak Co.), or any tackifiable material, and then followed by the directing the pigmentresin toner through a selective mask or stencil onto the tackifiable material resulting in a toner image sticking in an image configuration on the tackifiable material. Once again, to insure that the toner image is charged, the image can be exposed to the electrostatic charge generated by a corona discharge device. A pigment image is then formed with the resin solvent in the manner already described. Another ramification of this embodiment includes selectively tackifying the support surface in an image configuration and uniformly spraying the pigment-resin toner over the entire surface whereupon the toner adheres only in the tacky image areas.

The thickness of the pigment-resin toner image is not particularly critical and may be of any convenient thickness. Layers of about 1 and 50 microns in thickness have been found to work conveniently. The resultant pigment image after solvent treatment would be correspondingly thinner than the above thickness range for the pigment-resin toner.

The following examples further specifically define the present invention with respect to the method of forming a pigment image. The percentages in the disclosure, examples, claims are by weight unless otherwise indicated. The examples, below are intended to illustrate the various preferred embodiment of making a pigment image from an original pigment-resin toner image.

EXAMPLE 1 A xerographic plate having about a 40-micron-thick layer of vitreous selenium on an aluminum substrate prepared by the method as set forth in U.S. Pat. No. 2,970,906 to Bixby is uniformly charged by corona discharge to a positive potential of about 600 volts by the corona charging device set forth by Walkup in U.S. Pat. No. 2,777,957. The plate is then exposed under dark room conditions to an image using a light exposure of about 10 foot-candle-seconds of light, resulting in a formation of a latent electrostatic image. This latent image is then developed by cascade development using a standard carrier consisting of glass beads as set forth in U.S. Reissue Pat. No. to Carlson 25,136, U.S. Pat. No. 2,788,288 to Rheinfrank and U.S. Pat. No. 2,618,551 to Walkup and a toner consisting of about 40 parts polystyrene, 15 parts poly N-vinyl methacrylate, and five parts carbon black. This results in a formation of a toner image on the charged areas of the plate.

EXAMPLE II The toner image on the xerographic plate of example I is then electrostatically transferred to a sheet of aluminized Mylar which consists of a Mylar base 5-microns-thick and a submicron overcoating of aluminum. The charged pigmentresin toner image is then dipped into a bath of liquid trichloroethylene for about two seconds, withdrawn, and allowed to dry. At the end of this time, a pigment image having good resolution and high density is left on the aluminized Mylar substrate, while the resinous portion of the toner has been dissolved away.

EXAMPLE III The toner image of example I is transferred to the aluminized side of aluminized Mylar as in example II. The toner image is then inserted into a Standard Xerography Fuser Oven Model A available from Xerox Corporation for 2-6 seconds. The oven is an electrical heating device and includes an asbestos plate on which the Mylar is placed for insertion into the oven. The heaters operate on volts AC at 1320 watts and the temperature is maintained inside the oven around 400 F. The fixed toner image is next dipped into a solvent as in example ll dissolving away the resin leaving a pigment image on the aluminized Mylar substrate.

EXAMPLE IV The toner image of example Ill is formed and fixed on the aluminized Mylar. Before the fixed pigment-resin image is immersed in the solvent as in example II, a positive charge is applied to the fixed toner image by passing a corona discharge device (as in U.S. Pat. No. 2,777,957) over the surface of the Mylar carrying the fixed toner image. The image is then dipped into the solvent as in example ll yielding a pigment image on the aluminized Mylar of better quality than in example Ill.

EXAMPLE V A toner image is formed on a conventional xerographic plate having a vitreous selenium layer about 40-microns-thick on an aluminum substrate by the method of example I using a toner comprising 9 parts 35/65, copolymer from n-butyl methacrylate and styrene, one part polyvinyl butyral, and one part carbon black.

EXAMPLE VI The toner image of example V is electrostatically transferred to a sheet of aluminized Mylar as in example ll. The transferred pigment-resin toner image is then developed by immersing the sheet into a tank of liquid cyclohexane for about three seconds. The sheet is then removed from the tank and allowed to dry, and exhibits a pigment image having good resolution and high density.

EXAMPLE vn A sheet of conventional printing paper is uniformly dusted with a toner consisting of 9 parts polyvinyl toluene, and one part carbon black, to form a uniform layer of the toner on the paper sheet. A selective mask in the form of an image is then placed over the toner coated sheet. A positive electrostatic charge is then applied to the selected areas by means of the corona discharge device of US. Pat. No. 2,777,957 to apply a retained charge of about 100 volts potential in image configuration. The charging device and stencil are then removed and the sheet agitated by shaking several times to remove the toner in the uncharged areas. The pigment-resin toner image is then immersed in a bath containing methyl ethyl ketone for a period of about 4 seconds. The sheet is then removed from the beaker and allowed to dry. A good pigment image having high-quality resolution and density is obtained.

EXAMPLE Vlll A paper sheet is uniformly coated with a thin film of petrolatum. A stencil in the form of an image is then laid over the sheet. A thermoplastic resin consisting of 30 parts by weight of polystyrene, 10 parts by weight methyl polymethacrylate, 30 parts by weight butyl polymethacrylate, parts by weight o-acetoacetotoluidide, and 10 parts by weight carbon black is dusted over the stencil so as to form a toner image of the stencil configuration on the tackifiable sub strate. The stencil is removed and the toner image charged to a potential of about 80 volts. The plate is then immersed in a liquid bath of acetone for 5 seconds. The plate is removed from the bath and allowed to dry. A pigment image having high-quality resolution and density is formed by this method.

Although specific components and proportions have been stated in the above description of the preferred embodiments of this invention, other suitable materials and procedures such as those listed above may be used with similar results. In addition, other materials and changes may be utilized which synergize, enhance or otherwise modify the pigment image.

Other modifications and ramifications of the present invention would appear to those skilled in the art upon reading the disclosure. These are intended to be included within the scope of the invention.

What is claimed is: 1. A method of forming a pigment image from a pigmentresin image which comprises providing a substrate having a charged toner image held thereon, said toner comprising pigment and resin, and

removing at least some of said resin by exposing said image to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.

2. The method of claim 1 wherein the substrate is coated with a resin soluble in said solvent.

3. A method of forming a pigment image from a toner image which comprises providing a xerographic plate having a toner image comprising a pigment dispersed in a resin electrostatically held on said plate,

electrostatically transferring said image to a substrate, and

removing said resin by exposing said image to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.

4. a method of forming a pigment image from a pigmentresin image which comprises uniformly coating a substrate with a toner comprising a pigment dispersed in a resin,

forming an electrostatic image on said coated substrate by means of charging through a stencil in image configuration,

removing the uncharged pigment-resin toner image from said substrate, and

removing said resin by exposing said pigment-resin toner to an electrically insulating solvent for the resin, whereby a pigment ima e remains on said substrate. 5. A method 0 forming a pigment image from a pigmentresin image which comprises uniformly coating a substrate with a tackifiable material, selectively dusting said surface through a stencil with a toner comprising a pigment dispersed in a resin to form a pigment-resin image on said coated substrate electrostatically charging said image, and

removing said resin by exposing said pigment-resin image to an electrically insulating solvent for the resin whereby a pigment image remains on said substrate.

6. A method of forming a pigment image from a pigmentresin image which comprises selectively coating a substrate in image configuration with a tackifiable material,

uniformly dusting said surface with a pigment-resin toner,

removing said toner from the nonimage areas,

electrostatically charging said image, and

removing said resin by exposing said image to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.

7. A method of forming a pigment image from a pigment resin image comprising the steps of providing on a substrate a charged toner image including pigment and resin,

softening said resin, and

removing said resin by exposing the toner image to a solvent for dissolving away the resin leaving a pigment image on the substrate.

8. The method of claim 7 wherein the substrate is coated with a resin soluble in said solvent.

9. The method of claim 7 wherein said toner image is fixed to the substrate.

10. The method of claim 7 further including applying electrostatic charge to the toner image prior to softening the resin.

ill. The method of claim 7 wherein said removing step includes dissolving away less than all said resin for fixing the pigment image to the substrate with the remaining resin.

12. The method of claim 7 where the charged toner image on the substrate is provided by a method which comprises uniformly charging a xerographic plate,

exposing said charged plate to light in imagewise configuration to form a latent electrostatic image,

developing the latent electrostatic image with toner particles including pigment and resin to form a pigment-resin toner image,

transferring said toner image to said substrate.

13. The method of claim 12 further including bonding said toner particles to each other and to the substrate after the transfer of the toner image to the substrate.

14. The method of claim 13 wherein said bonding is accomplished by heating said toner particles.

15. The method of claim 14 further including applying electrostatic charge to said toner image after the toner particles are bonded to each other and the substrate. 

2. The method of claim 1 wherein the substrate is coated with a resin soluble in said solvent.
 3. A method of forming a pigment image from a toner image which comprises providing a xerographic plate having a toner image comprising a pigment dispersed in a resin electrostatically held on said plate, electrostatically transferring said image to a substrate, and removing said resin by exposing said image to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.
 4. a method of forming a pigment image from a pigment-resin image which comprises uniformly coating a substrate with a toner comprising a pigment dispersed in a resin, forming an electrostatic image on said coated substrate by means of charging through a stencil in image configuration, removing the uncharged pigment-resin toner image from said substrate, and removing said resin by exposing said pigment-resin toner to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.
 5. A method of forming a pigment image from a pigment-resin image which comprises uniformly coating a substrate with a tackifiable material, selectively dusting said surface through a stencil with a toner comprising a pigment dispersed in a resin to form a pigment-resin image on said coated substrate electrostatically charging said image, and removing said resin by exposing said pigment-resin image to an electrically insulating solvent for the resin whereby a pigment image remains on said substrate.
 6. A method of forming a pigment image from a pigment-resin image which comprises selectively coating a substrate in image configuration with a tackifiable material, uniformly dusting said surface with a pigment-resin toner, removing said toner from the nonimage areas, electrostatically charging said image, and removing said resin by exposing said image to an electrically insulating solvent for the resin, whereby a pigment image remains on said substrate.
 7. A method of forming a pigment image from a pigment resin image comprising the steps of providing on a substrate a charged toner image including pigment and resin, softening said resin, and removing said resin by exposing the toner image to a solvent for dissolving away the resin leaving a pigment image on the substrate.
 8. The method of claim 7 wherein the substrate is coated with a resin soluble in said solvent.
 9. The method of claim 7 wherein said toner image is fixed to the substrate.
 10. The method of claim 7 further including applying electrostatic charge to the toner image prior to softening the resin.
 11. The method of claim 7 wherein said removing step includes dissolving away less than all said resin for fixing the pigment image to the substrate with the remaining resin.
 12. The method of claim 7 where the charged toner image on the substrate is provided by a method which comprises uniformly charging a xerographic plate, exposing said charged plate to light in imagewise configuration to form a latent electrostatic image, developing the latent electrostatic image with toner particles including pigment and resin to form a pigment-resin toner image, transferring said toner image to said substrate.
 13. The method of claim 12 further including bonding said toner particles to each other and to the substrate after the transfer of the toner image to the substrate.
 14. The method of claim 13 wherein said bonding is accomplished by heating said toner particles.
 15. The method of claim 14 further including applying electrostatic charge to said toner image after the toner particles are bonded to each other and the substrate. 